package cn.tedu.sp06.fb;

import cn.tedu.web.util.JsonResult;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.stereotype.Component;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;

/**
 * @author 木木
 * @Email 1194660762@qq.com
 * @date 2021-08-16 14:11
 */
//商品降级类
@Component
@Slf4j
public class OrderFB implements FallbackProvider {
    /**
     * 设置针对哪个后台服务进行降级
     *  item-service: 只针对商品服务进行降级
     *  *:      对所有服务都应用当前降级类
     *  null:   对所有服务都应用当前降级类
     * @return
     */
    @Override
    public String getRoute() {
        return "order-service";
    }

    /**
     * 向客户端发回的降级响应
     *  - 错误提示
     *  - 缓存数据
     *  - 根据业务逻辑返回任意数据
     * @param route
     * @param cause
     * @return
     */
    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {
            @Override
            public HttpStatus getStatusCode() throws IOException {
                return HttpStatus.INTERNAL_SERVER_ERROR;
            }

            @Override
            public int getRawStatusCode() throws IOException {
                return HttpStatus.INTERNAL_SERVER_ERROR.value();
            }

            @Override
            public String getStatusText() throws IOException {
                return HttpStatus.INTERNAL_SERVER_ERROR.getReasonPhrase();
            }

            @Override
            public void close() {
                //用来关闭下面的输入流
                //ByteArrayInputStream 虚拟机中读取byte[]的流对象
                //不占用底层系统资源,不需要关闭
            }

            @Override
            public InputStream getBody() throws IOException {
                // JsonResult - {code:500, msg:xx, data:null}
                String json = JsonResult.err()
                        .code(500)
                        .msg("后台服务出错,请稍后重试")
                        .toString();
                //用 ByteArrayInputStream 封装 json 结果
                return new ByteArrayInputStream(
                        json.getBytes(StandardCharsets.UTF_8));
            }

            @Override
            public HttpHeaders getHeaders() {
                // Content-Type: application/json;charset=UTF-8
                HttpHeaders httpHeaders = new HttpHeaders();
                httpHeaders.add("Content-Type", "application/json;charset=UTF-8");
                return httpHeaders;
            }
        };
    }
}
